1) Field of the Invention
The present invention relates to a multi-row LED wiring member for mounting an LED element, and a method for manufacturing the same.
2) Description of Related Art
Optical semiconductor devices equipped with LED (Light Emitting Diode) elements have come to be used in various apparatuses such as general lights, televisions, mobile phones and displays for OA devices.
In these optical semiconductor devices, as LED packages that have been developed to meet the demand for thinning and mass production, there are conventional LED packages in each of which an LED element is mounted on a lead frame having electrically insulated pad portion and lead portion, a reflector resin portion is formed to surround the pad portion and the lead portion on the side where the LED element is mounted, and the inside space surrounded by the reflector resin portion on the LED-element mount side is sealed with a transparent resin portion.
In this type of LED package, for example, as shown in FIG. 7A, the lead frame 50 has a pad portion 51 and a lead portion 52 disposed with a space from the pad portion 51, and, on the upper surface and the lower surface of the pad portion 51 and the lead portion 52, a plating layer 53 for reflection or connection with external is formed. On the upper-surface side of the lead frame 50, an LED element 60 is mounted on the pad portion 51, and the LED element 60 and the lead portion 52 are connected via a bonding wire 54 or the like. Around the LED element 60, a reflector resin portion 55, which reflects light, is formed to surround the pad portion 51 and the lead portion 52. An inside space surrounded by the reflector resin portion 55 on the side where the LED element 60 is mounted is sealed with a transparent resin portion 56 made of a transparent resin.
As shown in FIGS. 8A-8C, a lead frame used for manufacturing this type of LED package is provided in the form of a multi-row LED lead frame in which individual lead frame regions (shown as individual rectangles drawn by alternate long and double short dashed lines in FIG. 8B) each configured of a combination of a pad portion 51 and a lead portion 52 are arrayed in a matrix, for the purpose of obtaining a large number of LED packages in bulk. As shown in FIG. 8B, each of the pad portion 51 and the lead portion 52 is connected with a coupling portion 57 (indicated by hatching in FIG. 8B) formed from a metal plate as a base material of the lead frame, and is coupled with pad portions 51 and lead portions 52 of other lead frame regions and with an outer frame portion 58 of the metal plate for manufacturing the multi-row LED lead frame, via the coupling portions 57.
In manufacturing of this type of LED package, as shown in FIG. 7B, the reflector resin portions 55 for the respective lead frame regions in the multi-row LED lead frame are formed in bulk as covering the coupling portions 57, the LED elements 60 are mounted and fixed on the pad portions 51 surrounded by the respective reflector resin portions 55 and are subjected to wire bonding or the like, the transparent resin portions 56 are formed in the inside spaces thereof, and then a part of the reflector resin portions 55 formed in bulk and a part of the coupling portions 57 are simultaneously cut along cutting portions between the respective lead frame regions.
As shown in FIG. 7A, this cutting process produces individual LED packages each having the pad portion 51 and the lead portion 52 uncovered on the lower surface side to be electrically connectable with an external substrate. On a side face of each LED package, the coupling portion 57 of the lead frame is exposed as a part of the cut surface together with the reflector resin portion 55.
A conventional LED package having such a configuration is described, for example, in Japanese Patent Application KOKAI No. 2013-232506.
In addition, conventionally, in an LED lead frame, a bright Ag plating layer is formed on the upper surface of the pad portion and the lead portion to enhance light reflection characteristics. For the purpose of attaining a glossiness of 1.0 or more, a brightener containing Se or S is used as an additive in the Ag plating solution.
A technique for forming an Ag plating film having a glossiness of 1.0 or more by using such an Ag plating solution is described, for example, in Japanese Patent Application KOKAI No. 2015-124427.
As described above, regarding LED package manufacturing, for the purpose of obtaining a large number of LED packages in bulk, there is used a multi-row LED lead frame configured so that a pad portion 51 and a lead portion 52 in each lead frame region as shown in FIG. 8B are coupled with pad portions 51 and lead portions of other lead frame regions and with an outer frame portion 58 of a metal plate, which is for manufacturing a multi-row LED lead frame, via coupling portions 57.
Also, the LED lead frame is provided with a reflective plating layer formed, by Ag plating, on the outermost layer of the pad portion and the lead portion of the metal plate, which serves as a lead frame substrate, for improving the reflectance of the LED element mount region.
This Ag plating layer is a bright Ag plating having a glossiness of 1.0 or more and formed by using an Ag plating solution to which a brightener is added in an Ag plating bath as described above. However, forming a bright Ag plating using an Ag plating solution containing a brightener added to an Ag plating bath requires concentration control of the brightener in the Ag plating bath, and furthermore, addition of the brightener raises the product cost.
The present invention has been made in view of the above problems, and it is an object of the present invention to provide a multi-row LED wiring member and a manufacturing method therefor in which the reflectance of the surface of a reflective plating layer can be maintained without addition of a brightener.